Status Report

NASA Hubble Space Telescope Daily Report # 3779

By SpaceRef Editor
January 20, 2005
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NASA Hubble Space Telescope Daily Report # 3779

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science

DAILY REPORT        # 3779



ACS/HRC 10192

Jupiter’s Upper Stratospheric Hazes Probed with Ganymede

I propose to observe a disappearance of Ganymede behind the dark limb
of Jupiter with five filters of the ACS/HRC camera. Two exposures in
each filter can be taken during such an event. The images will provide
the spectral variation of the altitude of the apparent limb of
Jupiter. The altitude of the apparent limb is dependent on the
presence of hazes in Jupiter’s stratosphere. Hazes of vertical optical
depths below 0.001 could be detected with these observations,
providing an extremely sensitive probe of high hazes. The observations
probe altitudes levels near the 1-mb pressure level, for which we have
very limited data. The creation of aerosols, their growth, and their
transport by winds is currently a mostly theoretical study. It would
significantly benefit from constraints derived from the proposed
observations. ACS/HRC is the only instrument capable of the required
spatial resolution in the ultraviolet. Furthermore, a favorable
geometry of Ganymede’s orbit occurs only once every six years. This
proposal achieves unique results with a minimum of HST time.

ACS/HRC 10441

Characterizing a Newly-Found Extrasolar Planet

We propose to observe transits of the newly-discovered extrasolar
planet TRES-1 using {1} ACS/HRC to obtain precise time-series
photometry of the transit, and {2} NICMOS to measure the strength of
water vapor absorption in the planetary atmosphere. The visible light
curve will permit an accurate estimate of the planet’s diameter by
resolving uncertainty concerning the diameter of the parent star, and
the water vapor observation can be used to test models of the
structure, clouds and composition in the planet’s upper atmosphere.

ACS/HRC 9059

UV/Visible Spectroscopy of Asteroid 762 Pulcova and its
Newly-discovered Moon

We propose to acquire separate, comparative, and simultaneous spectra
of asteroid 762 Pulcova and its satellite. We will compare our results
with those we obtain[ed] in a program approved in cycle 9 for 45
Eugenia and its moon. We discovered both of these moons using
ground-based adaptive optics — Eugenia in 1998, but Pulcova only in
the last year. We can now compare two systems that both have primaries
of the relatively uncommon F-like spectral class. We will determine
whether the surface compositions are similar or different in the
parent-satellite pair and test hypotheses concerning satellite
production mechanisms. Our fits to the orbits yield a surprisingly low
density for Eugenia of 1.2 g/cm^3, but that of Pulcova is 50% higher.
F-type spectra are similar to the common C-types, but differ by the
lack of a UV-band or UV-dropoff and by subtle, but measurable
differences in the spectral slope. Both the UV-region and the
existence of subtle absorption features in the near-IR {approx 9000
Anstroms} are diagnostic of the specific differences between F-, C-,
and {Bus’} X-class. HST is required because the ground-based adaptive
optics is not available in the UV and cannot yet provide adequate
resolution in the visible.


ACS CCDs daily monitor- cycle 13 – part 1

This program consists of a set of basic tests to monitor, the read
noise, the development of hot pixels and test for any source of noise
in ACS CCD detectors. The files, biases and dark will be used to
create reference files for science calibration. This programme will be
for the entire lifetime of ACS.

ACS/WFC 10452

HST/ACS Mosaic of M51

A six-pointing ACS WFC mosaic of the galaxy pair M51 will be obtained
in four filters, B, V, I and H-alpha. Four orbits per pointing will
allow high-quality S/N images of the entire galaxy.

NIC3/WFPC2 10403

Ultraviolet Imaging of the UDF

The Hubble Deep Field North has uninterrupted observations at
wavelengths from Far-UV through NICMOS H-band, but the UDF goes no
bluer than B-band. We propose to complete the UDF coverage with deep
ultraviolet imaging of the Ultra-Deep Field {UDF} with the ACS-SBC in
the Far-UV {1500 Angstrom} and WFPC2 in the Near-UV {F300W}. We will
reach point source limits of ABmag=28.5, a factor of ten fainter than
the GALEX ultradeep surveys. Our dataset will add to the value of the
UDF legacy, and requires the unique capabilities of HST. In the spirit
of the UDF, we submit this proposal in the Treasury category. We
request a modest allocation of observing time for a Treasury program:
62 orbits. We will provide science quality images and photometric
catalogs to enable a range of research topics by the community. The
science goals of the team are to investigate the episode of strong
star formation activity in galaxies out to z=1, through the rest-frame
FUV luminosity function and the internal color structure of galaxies.
Far-UV number counts suggest that moderate redshift {z~0.5} starbursts
are undergoing a single, rapid burst of star-formation. We will
investigate this result by measuring the faint-end slope, alpha, of
the luminosity function. We will measure the star formation properties
of moderate redshift starburst galaxies and compare their morphologies
in the UV, optical, and near-IR. This catalog of starbursts will also
be important to the astronomical community in correlating unobscured
star-formation with the sources detected in the Spitzer Space
Telescope legacy observations of the field. With the high spatial
resolution data, will set strict limits on the flux escaping in
intermediate redshift {1


NICMOS Post-SAA calibration – CR Persistence Part 1.

A new procedure proposed to alleviate the CR-persistence problem of
NICMOS. Dark frames will be obtained immediately upon exiting the SAA
contour 23, and every time a NICMOS exposure is scheduled within 50
minutes of coming out of the SAA. The darks will be obtained in
parallel in all three NICMOS Cameras. The POST-SAA darks will be
non-standard reference files available to users with a USEAFTER
date/time mark.


Significant Spacecraft Anomalies: (The following are preliminary
reports of potential non-nominal performance that will be

HSTAR 9669: OTA PTAS review revealed GS Acquisition (1,2,2) @
223/1330:10Z required multiple attempts to enter Coarse Track.
Acquisition was successful and no science was affected.



                              SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS Gsacq                  13                        13
FGS Reacq                   2                          2
FHST Update                24                        24


SpaceRef staff editor.